Boiler control



Atari] 27, 1937. N. c. PRICE l 2,078,341

oILER cQuTRoL Filedpsepf. so, 1933 ATTORNE Patented Apr. 27, 1937 UNITED STATE-s PATENT OFFICE ,r

1 Claim.

My invention relates to means for governing the temperature of superheated steam flowing from a boiler variously designated as of the semiflash, series tube, or forced circulation type.

5 Boilers of this type usually comprise at least one tube of considerable length heated by a heating mechanism such as a hydrocarbon burner. Feed water is introduced into the inlet end of the tube and is heated as it progresses through the tube,

nally issuing from the tube outlet as super` heated steam.

An object of my invention is to provide means for governing or controlling closely the temperature of steam generated by a. boiler of the men- 15 tioned type.

circulation boiler with the boiler controlr of my invention incorporated therewith.

Figure 2 is a diagram of a modied valve arrangement adjacent the inlet of the-boiler.

In its preferred form, the boiler control of my invention includes a forced circulation type boiler having adjacent its steam zone a thermostat effective above a predetermined temperature to permit the flow of relatively cool water into a jacket in thermal union with a portion of the boiler tube in advance of or at the thermostat.

Forced circulation boilers are customarily provided with regulators for controlling in general the pressure and temperature of the steam issuing therefrom. Such regulators usually govern the supply of heat from the burner and the supply of feed water. Some of them include means for injecting additional feed water into the boiler tubev just in advance ofthe thermostat for 0 minimizing 4the fluctuations in temperature of the issuing steam. Exemplary regulators and controls for forced circulation boilers are shown in the various patents of Abner Doble, particularly No. 1,955,274, dated April 17, 1934 and Warren Doble, particularly No. 1,898,083, dated February In embodying my own invention I utilize any suitable general regulating or control system and any suitable heating and feed water supplying means, such for example as show in the patent of Marcus Lothrop, No. 1,935,981, dated November 21, 1933. Since any suitable boiler details and control system can be utilizedjthey are not illustrated especially herein.

-- The present mechanism is incorporated with (Cl. 122-479) l a heated boiler coil 6 of considerable length; the' coil having an inlet 1 and an outlet 3, ilow from which is governed by a throttle valve 9. Between the inlet 1 and the outlet 8 but near the outlet is a thermostat II arranged in thermal union with the boiler tube 6 to be responsive to the temperature therein. Since the coil 6 is properly heated, water which is introduced into the inlet from a force pump I2, flows past a check valve I3 and through the tube, being gradually heated and converted into steam and finally issues from the outlet 8 under control of thevalve 9. The heating means for example includes an electric motor 3| deriving electricity from a battery 32 under control of a manual switch. 33 and a switch 34 opened by steam pressure in excess of a predetermined amount. The motor 3I drives a blower 36 to aspirate fuel from a carburetor 31. This is ignited by spark plug 38 energized by an electric coil 39 so that the products of combustion travel through the boiler casing 4I over the vtube 6.

In accordance with my invention I provide means for damping or suppressing major fluctuations in the temperature of the outiiowingv steam. A ductlIIl is connected to any suitable source of water, such as the discharge side of the pump I2, and leads to a jacket I6 in thermal union with an appropriate portion of the coil G preferably slightly-in advance of the thermostat II. A return duct I1 extends from the jacket to any suitable point of discharge, usually being connected through a check valve I8 to the inlet 1 of the boiler tube 6 beyond the valve I3. Flow through the ducts I4 and I1 and the jacket I6, the re- .pair of electrical contacts 21 and 28. The contact 21 isadjustably mounted on an insulated arm 29, While the contact 28 is mounted to move with the movable member of the thermostat II and is connected to ground by a wire 3I.

In the operation of the device, as the temperature of the fluid passing the thermostat II exceeds a predetermined temperature, the contact 28 is moved to abut contact 21 and since the master switch 24 is closed, the electrical circuit from the battery 22 to the solenoid 2I is completed and the solenoid is actuated to open the valve I9. Some of the feed water discharged by the pump I2 is shunted through the duct I4- to the jacket Cil perature ofthe tube liquid is reduced below the predetermined temperature and the responsive thermostat II separates the contacts 21 and 28. The solenoid 2| is deenergized and the valve I9 is closed interrupting the supply of uid to the jacket I6. 'Ihe temperature ofthe fluid flowing through the' tube 6 is therefore again permitted to rise.

In Figure 2 there is illustrated a modification in which the chief alteration is a transposition of the valves I3 and I9, the remainder of the structure being identical except that the valve I9 is moved toward closed position when the solenoid 2l is energized. The resistance to flow through theA open valve I9 is less than through the shunt path formed by the ducts I4 and I'I and the jacket I6 so that little' or no water flows to the jacket, but when theivalve I9 is closed or partially so, water is diverted -to flow through the shunt path.

In accordance with these arrangements there is a continual hunting or vvariation of the temperature, adjacent the thermostat I I either side of the predetermined temperature but such hunting or fluctuation is of relatively small magnitudeso that the temperature of the steam issuing from the outlet 8 is relatively constant within very close limits. There is no alteration of the mass of fluid flowing vin the tube 6 adjacent the thermostat because there is no addition of liquid for temperature correction purposes and the operation of the boilerl is not upset from that aspect. Since there is no introduction into the tube 6 of a small additional quantity of water which must 'almost immediately be evaporated there is no deposit of carbon or scale in the main tube adjacent the thermostat II. While the quantity of water flowing throughy the jacket I6 is relatively small and can in fact be so small as to be evaporated in the jacket I6, I ordinarily prefer that the quantity of liquid be sufllciently large so that its temperature is not greatly increased but increased just sufficiently to heat the feed water going into the inlet 1 in an amount which will not impair the general eiilciency of the structure.

It is to be understood that I do not limit myself to the form of the boiler control shown and described herein, as the invention, as set forth in the following claim may be embodied in a plurality of forms.

I claim:

A control for a boiler characterized by a long, heated tube having an inlet and an outlet, comprising a heat exchanger intermediatel the ends of the tube, a thermostat near the outlet end of said tube and responsive to the temperature thereof, means for forcing fluid into the inlet of said tube, means for diverting part of said fluid from the inletthrough the heat exchanger and'directly back to said inlet, and means under the control of said thermostat for controlling-said diverting means to increase the quantity of water diverted through the heat exchanger upon increase of said temperature.

NATHAN C. PRICE. 

